Process of producing flints by means of extrusion



United States Patent PROCESS OF PRODUCING FLFNTS BY MEANS OF EX I-RUSION Walter Bungardt, Essen-Bredeney, Germany, assignor. to Th. Goldschmidt A.-G. Chemische Fabriken, Essen, Germany, a German corporation 4 Claims. (Cl. 75152) This invention refers to the manufacture of pyrophoric flint material in rod or like shape and has. as one of its primary objects to provide means affording subjection of an ingot of suitable alloy to an extrusion press having a die opening whose cross-section corresponds to that of the finished flint rod.

It is another object of the inventionto-p rovidemeans conducive we most simple and economical production of flint material in rod formation or like shapes,,which is markedly improved in its pyrophoric propertiesand substantially free from any objectionable impurities.

It is a further object affording the manufacture of flint material with improved exactitude of size without the necessity of machining or other subsequent working which would cause additional expense and considerable delay in the obtainment of the desired end product.

Cerium-iron alloy flints are usually made by casting. It has been proposed to make flints of this kind by the extrusion process which is more economical than casting. The known attempts inthisv direction have failed. It was found that the pyrophoric properties of the alloy were lost during the extrusion process, hence the process has been described intechnical literature as completely useless.

The present invention proceeds from the recognition that the diminution of pyrophoric properties during extrusion is to be attributed to the fact that, on extrusion, the cerium-iron crystals, to which the pyrophoric action of the cerium-iron alloys is to be ascribed, are shattered and that consequently a larger quantity of eutectic matrix is necessary in order to embed sufliciently the fragments of the cerium-iron crystals so that they are protected against breaking out when subjected to friction by the friction Wheel of a lighter. Researches have shown that the necessary quantity of eutectic matrix increases with the increase in size of the cerium iron crystals in the ingot introduced into the extrusion press.

The eutectic matrix has not only the task of embedding the cerium-iron crystals and protecting them from breaking away, but also of increasing the pyrophoric properties of the cerium-iron crystals. The eutectic matrix is readily oxidizable, but oxidation manifests itself not in spark formation on friction but only in heat production; however this heat production favors the flaming of the pyrophoric crystal fragments. The best cerium-iron alloy for flints produced by casting consists of about 30 to 40% iron, the remainder being cerium. The amount of eutectic matrix increases with the decrease in the iron content.

In the process for the production of pyrophoric flints from cerium-iron alloys, by means of extrusion presses according to the present invention, the iron content may be lowered to to 25% of the total alloy-age. It was found that with ingots with an iron content lowered to from 15 to 25%, when they are produced in a normal manner, such a quantity of eutectic groundmass or matrix of the invention to providemeans.

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2. must be on hand that the fragments'or fission-products of the cerium-iron crystals resulting from extrusion pressing remain sufliciently anchored or tied in the matrix. The required amount ofeutectic groundm-ass or matrix for extrusion pressing may be reduced as the cerium-ironcrystals are-correspondingly smaller in the ingot used for extrusion pressing.

The crystals shouldnot be below a minimum size, otherwise they lose their pyrophoric properties. It has now been found, however, that by the use of inoculant' additions, i. e. additions resulting from the production of more numerous but smaller crystals, or by accelerated cooling of the ingot, such a diminution in size of the cerium-iron crystals can be obtained that, on, the one hand, the pyrophoric properties are not substantially influenced, while, on the other hand, the cerium-iron crystals can slip past one another. during extrusion without shattering so that an increase in eutectic matrix is notnecessary. The process according to the present invention can therefore be carried out by utilizing cerium-iron alloys with an-ironcontent of more than and up to and an inoculant addition, e. g. zirconium. The .amount of this addition must not be so, large that it substantially affects the pyrophoric properties of the alloy. Additions of up to 1% zirconium, for example, are sufficient.

Particularlyadvantageousinoculant additions are such elements that do not form with the other alloying elements any alloy constituents which are-liquid below the extrusion temperature. Alloying constituents which are liquid at the extrusion temperature have a detrimental effect on the extrusion operation.

As the melting point of cerium-iron alloys decreases with reduction in the iron contents, such a reductionhas advantages during casting. It diminishes, for example, the loss by burning. Onthe other hand, it diminishes also" the hardness of the alloy so that the friction wheel of the lighter rubs more severely against the flint and thereforeuses'it up more rapidly. It therefore alloys with a low iron contentiare used in accordance with the invention, it is useful to add to them hardness-increasing elements, for example tin, magnesium, cadmium or zinc, in a quantity which does not substantially affect the pyrophoric properties of the alloy.

Where reference has been made above to cerium, this term is intended to include the misch metal customary in the trade which, in addition to cerium, is always accompanied by other rare earths, for example lanthanum.

The high oxidizability of the cerium-iron alloys reduces their lastingness. The alloys are destroyed in time by oxidation from the air, in particular under the high temperatures of hot and moist climates.

Cerium-iron flints therefore usually have at protecting covering. It has now been found that the lastingness is increased to an extraordinary degree if the cerium-iron alloy is plunged in oil when in hot condition. This can easily be effected in the case of extruded flints by leading into oil the rod of material delivered hot from the extrusion press, with or without an intermediate passage through an atmosphere of inert gas which, for example, may be argon, hydrogen or nitrogen. This method of improving the lastingness, however, is not limited to extruded flints.

The lastingness can also be improved in the case of extruded material by surrounding the ingot with a coating metal and then extruding it, so that the emerging rod of cerium-iron alloy is surrounded by a thin coating of the protecting metal. Aluminium has been found specially suitable for this purpose. The ingot can either be wrapped with aluminum foil, introduced into an aluminium tube, or have aluminium cast around it.

The following examples are given to demonstrate the features of the invention:

'Ingots of a diameter of approximately 30 mm. are

produced by pouring into special steel ladles or molds, packed with sand, molten compounded material consisting of approximately 30 parts by weight of iron while misch metal constitutes the remainder of said material.

This compounded material is heated to approximately 1200 C., preferably 1 150 C. while the temperature of the mold is approximately 100 C. The period of cooling until the mold is opened amounts to approximately 30 minutes.

The ingots thus obtained have a temperature of approximately 450 C. and are then subjected to the action of an extrusion process operating under a pressure of approx imately 16,000 leg/cm. in the same manner as described in Example 1.

Many other changes and modifications of the invention may be made without limiting the same and without departing from the scope of the invention.

This application is a continuation-in-part of application Serial No. 117,069, filed September 21, 1949, now Patent No. 2,660,301.

What is claimed as new and desired to be secured by Letters Patent is:

1. The process of producing flint material in rod formation comprising the steps of preparing an ingot by adding to an alloy containing approximately 25% to 40% iron, with cerium being the remainder, an inoculant suflicient to influence the crystal formation of said alloy without substantially changing the pyrophoric properties thereof,

' and subjecting said ingot thus prepared to the action of an extrusion press under a pressure of about 16,000 kg./cnr. and at a temperature of about 450 C. for obtaining an extruded material upon discharge of the latter through .a die opening having a cross-section corresponding to that of the finished flint rod.

2. In the process of producing flint material in rod formation; the step of preparing an ingot by adding to an alloy containing approximately 25% to 40% iron, with cerium being the remainder, approximately 0.05% to 1% of zirconium as an inoculant, whereby the crystal formation of said alloy is influenced without substantially changing the pyrophoric properties thereof.

*3. In the process of producing flint material in rod formation; the steps of adding to an alloy containing approximately 25% to 40% iron, with cerium being the remainder, an inoculant sufficient to influence the crystal formation of said alloy, further adding at least one hardness-increasing element selected from the group consisting of tin, magnesium, cadmium and zinc sufficient to obviate any substantial decrease of the pyrophoric properties of said alloy, and thereafter forming said alloy into an ingot prior to its transformation to flint material in rod formation.

4. The process of producing flint material in rod formation comprising the steps of preparing an ingot by adding to an alloy containing approximately 25% to 40% iron, with cerium being the remainder, approximately .1=5% of zirconium as an inoculant, whereby the crystal formation of said alloy is influenced without substantially changing the pyrophoric properties thereof, and subjecting said ingot thus prepared to the action of an extrusion press under a pressure of about 16,000 kg./crn. and at a temperature of about 450 C. for obtaining an extruded material upon discharge of the latter through a die opening having a cross-section corresponding to that of the finished flint rod.

References Cited in the file of this patent FOREIGN PATENTS 

1. THE PROCESS OF PRODUCING FLINT MATERIAL IN ROD FORMATION COMPRISING THE STEPS OF PREPARING AN INGOT BY ADDING TO AN ALLOY CONTAINING APPROXIMATELY 25% TO 40% IRON, WITH CERIUM BEING THE REMAINDER, AN INOCULANT SUFFICIENT TO INFLUENCE THE CRYSTAL FORMATON OF SAID ALLOY WITHOUT SUBSTANTIALLY CHANGING THE PYROPHORIC PROPERTIES THEREOF, AND SUBJECTING SAID INGOT THUS PREPARED TO THE ACTION OF AN EXTRUSION PRESS UNDER A PRESSURE OF ABOUT 16,000 KG./CM.2 AND AT A TEMPERATURE OF ABOUT 450* C. FOR OBTAINING AN EXTRUDED MATERIAL UPON DISCHARGE OF THE LATTER THROUGH A DIE OPENING HAVING A CROSS-SECTION CORRESPONDING TO THAT OF THE FINISHED FLINT ROD. 